How to get Search icon and search box toggle as per demo

I am having trouble getting the search block, the same as in the demo, i.e. a search icon, that when clicked brings up the search block. And the search icon is visible in mobile. For reference, I currently have Search API installed and the search block is a block that has been created automatically via this. I don't suppose this is any different to using the existing search block that ships with Drupal (but is not used, in my case), but I just thought I would mention it anyway. So, unless I have missed a setting somewhere to get the search like the demo, my questions are: 1) How do you only get an icon in the menu. (I see that I now have the option to add an icon, but text still has to be entered for the menu item, which I don't want? 2) How do I set the search block to be hidden until someone clicks on the search icon? Thanks.